hello Aina,
Check for the following things.
does your really is still proper?
another case it migh be that your PC is now giving the pervious output what is latched by you program in the first time. so when ever you start you programe you must define all the input and the outputs. as soon you start the programe just send the a oppsite conditon on the prallel port wht you send to switch it on. now when ever you will start you code the the fan will go OFF first and as soon you press the on swith it will get ON.
i hope you got a idea what to do?